Lighting apparatus having asymmetric light intensity distribution of compensating for low contrast ratios of LCD panel

摘要

A lighting apparatus for illuminating a liquid crystal display (LCD) panel from behind is disclosed, wherein the LCD panel, when illuminated uniformly, exhibits asymmetric contrast ratios as viewed in a vertical direction. The apparatus comprises a light guide panel having a multitude of light reflecting dots on a reflecting surface opposite to the LCD panel, and a light source for injecting light into the light guide panel in a horizontal direction through a first edge of the light guide panel, so that the light propagates through the light guide panel toward the opposite edge of the panel and irregularly reflects off the dots toward the liquid crystal display panel. The light reflecting dots in a lower portion of the reflecting surface have a lower density than those in an upper portion of the reflecting surface, and each of these portions of the reflecting surface has a density increasing as a function of distance from the first edge of the light guide panel so that the LCD panel has equal brightness at the upper and lower portions when viewed at an angle substantially equal to 90° and an angle smaller than 90°, respectively.